This application is related to Japanese Patent Application No. H11-315528, filed Nov. 5, 1999, the entire disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an air belt apparatus for protecting passengers of moving vehicles during a collision, and,more particularly, to an air belt and an air belt apparatus inflated by gas from a gas generator.
2. Description of Prior Art
Japanese Unexamined Patent Publication No. 5-85301 describes a typical air belt apparatus. FIG. 6 is a perspective view showing the air belt of that publication. The air belt apparatus 1 includes an inflation belt 2, which extends diagonally from a right side to a left side of the passenger, a webbing 2a, which is connected to the inflation belt 2, a lap belt 3, which is extended from the right side to the left side of the passenger, a buckle device 4, which is arranged on the floor or the like of a vehicle, a tongue 5, which is engaged with the buckle device when fastening the belt, and an anchor 6, which guides the webbing 2a. 
The webbing 2a is a normal belt similar to that of a typical, conventional belt and is slidably inserted through the anchor 6. One end of the webbing 2a is wound and connected to a retractor 7 (ELR) incorporating an emergency locking mechanism seat belt. The seat belt retractor 7 is fixed to the vehicle body. The inflation belt 2 is seamed and connected with the expansion belt 2, and the other end is connected with the tongue 5. The lap belt 3 is a normal belt similar to that of a normal seat belt. One end of the lap belt 3 is connected to the tongue 5 and the other end is connected to the seat belt retractor (ELR) 8, which is fixed to the vehicle body. A gas generator 9, which is activated during emergencies, such as during a collision, to generate high-pressure gas, is connected to a buckle device 4. Gas flows from the gas generator 9 to the inflation belt 2 through a passage extending between the tongue 5 and the buckle device 4. The inflation belt 2 is formed by folding a wide strip-like bag into a narrow strip and accommodating the folded bag in a cover. Under normal situations, the inflation belt 2 is held in a strip-like manner. The air belt apparatus 1 is used in the same manner as an ordinary seat belt apparatus. When the gas generator 9 is activated during collision of the vehicle, the inflation belt 2 is inflated, as shown by the broken lines, to protect the passenger.
In this typical air belt apparatus, the inflation belt 2 is connected to the webbing 2a, which is wound in the retractor 7. This is because the inflation belt 2 is thicker than the webbing 2a thereby making it difficult to pass through the anchor 6 and be wound in the retractor 7.
In this typical air belt, the inflation belt 2 is less rigid than the webbing 2a and thus difficult to be kept in a flat belt-like state. This makes the passenger uncomfortable.
In this typical air belt, the hardness in the lateral direction is low at the inflation portion. Thus, the inflation portion easily bends into an overlapped state at the shoulder anchor portion. When bending and overlapping occurs, unwinding and winding actions may not be smooth and the restraining capability during a collision may decrease. Thus, the length of the inflation portion is such that passage through the shoulder anchor portion is restricted.
In this typical air belt, the hardness of the inflation portion in the longitudinal direction hinders smooth winding and unwinding actions.
It is an object of the present invention to provide an air belt that can be passed through an anchor and wound directly to a retractor even if the webbing is omitted.
It is an object of the present invention to provide an air belt having satisfactory comfort.
It is another object of the present invention to prevent bending and overlapping in order to obtain a further satisfactory restraining capability.
It is another object of the present invention to provide an air belt that enables smooth winding and unwinding actions.
An air belt according to the present invention includes a hollow strip-like cover and a bag arranged in the cover, wherein the air belt is inflated by supplying gas into the bag, air belt being characterized in that the hardness of the cover in the lateral direction is greater than the hardness in the longitudinal direction.
The air belt of the present invention more easily maintains a flat belt-shape because the hardness of the cover in the lateral direction is greater than the hardness in the longitudinal direction. Further, since the hardness in the longitudinal direction is decreased, the air belt flexibly bends in the longitudinal direction. This enables the air belt to be inserted through an anchor and be wound directly to the retractor.
To make the hardness of the cover in the lateral greater than the longitudinal direction, at least some of the wefts of the cover are monofilaments or modified yarns. Alternatively, yarns thicker than those used as the warps may be used as the wefts.
It is preferred that the cover have a tearing portion that is torn when the bag is inflated. The tearing portion is seamed by a seaming thread that is broken when the bag is inflated.
In the air belt of the present invention, a mesh webbing is arranged between the cover and the bag. The mesh webbing accommodates the bag and inflates together with the bag when the bag is inflated. The mesh webbing protects the bag. Since the mesh webbing is inflated together with the bag, the inflation characteristics of the bag are not affected.
An air belt apparatus according to the present invention inflates the air belt with a gas generator.